We plan to continue our investigation of the role of glutamine synthetase in the regulation of the synthesis of glutamine synthetase in Klebsiella aerogenes. In particular, we shall attempt to discover whether the control is positive or negative and whether molecules other than glutamine synthetase are involved. We shall investigate the regulation of the enzymes of nitrogen metabolism in Saccharomyces cerevisiae. In particular we shall attempt to discover whether glutamine synthetase is involved in regulation in this eukaryotic organism.